>
> Ligia Pimentel schrieb:
> > Yes, a very wide table (many columns) will be less efficient than a table
> > with less columns (this is a matter of relational concepts and
> > normalization).
> >
I must admit that I do not understand this comment:
what has normalization to do with performance?
As far as I understand normalization it is meant to avoid *redundance* and
not to improve performance. Actually normalization in general decreases
performance becaus a join over several tables is much less efficient than a
select on a single table. In most (but not all!) cases it is more important
to avoid inconsistencies due to redundance however.
The only disadvantage of a table with many columns that I can imagine occurs
when the columns are addressed by name rather than by index. If postgres
implements the column lookup by a linear search through all column names,
this can become an issue in very wide tables.
Even in that case I do not know whether a breakup in n tables might increase
performance.
Christoph Dalitz
